a) Field of the Invention
The invention is directed to a method for photoablation in the field of dermatological medicine in which an area on a surface of the skin is swept over by a laser beam and thus subjected to treatment. It is further directed to an arrangement for photoablation in the field of dermatological medicine by means of laser radiation with optical component groups for protected guidance of the laser radiation, with closing or terminating optics at the point where the laser radiation passes into the open air, and with a tubular outlet channel by which the free laser radiation is surrounded proceeding from the terminating optics and which has an outlet opening for the laser radiation at its end portion opposite from the terminating optics, wherein, during treatment, the laser radiation and the outlet channel are directed toward an area to be treated on the surface of the skin and the outlet opening is positioned near the area.
b) Description of the Related Art
When a continuous laser beam strikes the skin for longer than 10 milliseconds, electromagnetic energy is converted into thermal energy which can be used to coagulate diseased tissue. If short laser pulses with a pulse duration in the range of nanoseconds and microseconds are used for treatment, mechanical-destructive tissue effects can be achieved without substantial thermal damage to the skin or to the biological matter in the target area.
It is known to use laser radiation for removal of material in this almost non-thermal process, also called photoablation. This possibility is already made use of all over the world, for example, to treat bone cartilage and hard tooth tissue, as well as in dermatological therapy. In dermatology, there is, above all, the possibility of treating various skin alterations from disfigured tissue to tumors.
At present, lasers are used in dermatology worldwide for the treatment of burns, for removal of tattoos and for skin renewal (resurfacing). This already indicates that such therapy is used predominantly for improving the quality of life of the patient and for cosmetic adjustment.
Medical-engineering instruments for carrying out the therapies mentioned above basically comprise a laser radiation source and a handpiece which serves to direct the laser radiation emitted by the laser radiation source to the target area of the part of the body to be treated. In order for the handpiece to be constructed with small dimensions and for the purpose of convenient handling with the least possible hindrance, the laser radiation source and handpiece are usually separated structurally and spatially, wherein a beam guiding unit is provided for transmitting the laser radiation from the radiation source to the handpiece. The beam guiding unit can comprise a plurality of rigid transmission members which are connected with one another in an articulated manner or as a flexible fiber-optic device. The handpiece has outlet optics and an outlet opening for the laser radiation which is to be directed to the target area.
DE 44 01 989 A1 describes a medical handpiece which serves to direct a laser beam emitted from a laser radiation source onto the part of the body to be treated. This handpiece comprises a housing and a laser radiation source integrated in the housing. By integrating the laser radiation source in the housing, the beam guiding unit can be omitted entirely, so that the handling of the medical handpiece is not impaired by mechanically restricted movement.
A recurring problem in ablation of biological matter by laser radiation and in the use of handpieces consists in that the particles removed from the treated surface impair the air quality in the immediate environment of the treatment location and also in the handpiece itself, e.g., in the outlet channel for the laser radiation. The particles settle on the outlet optics for the optical beam path in the handpiece in a disadvantageous manner and lead to unpleasant odor for the patient and the person carrying out the treatment because biological matter also evaporates during the treatment.
In order to prevent this, it is necessary to remove the detached particles and the resulting fumes from the place of origin or at least to prevent the particles from settling on the optics in the handpiece. For this reason and, finally, also for the purpose of protecting the medical personnel and the patient from the harmful and foul-smelling fumes, exhaust systems have been developed which, as separately engineered units, comprise a base device containing a suction source and a filter, and a tube-prefilter system. Accessories for devices of the kind mentioned above include suction tubes which must be positioned in the vicinity of the treated location so that ablation debris or ablation waste products can be intercepted. The disadvantages of this device consist on the one hand in that the suction tube arranged in the vicinity of the treatment location restricts the freedom of movement of the handpiece during the laser treatment and, on the other hand, when changing the treatment location it is necessary to readjust the handpiece or the target direction of the laser beam so that the suction device remains effectively directed to the treatment location.
In further conventional handpieces such as those described, e.g., in U.S. Pat. No. 5,344,418, flow channels for gases or air are provided inside the handpiece which end in the vicinity of the outlet opening for the laser beam and, from that location, direct a flow of gas or air to the location to be treated. This primarily provides for a cooling (although an uneven cooling) of the treated skin region, but also results in a secondary effect at least in that the ablation waste products are blown away from the handpiece and from the treated skin area. This also does not solve the problem of contaminated air and unpleasant odor. Moreover, the treated skin portion is not thermally affected in a uniform manner, since the gas flow or air flow must pass over the target area laterally, wherein the temperature of the gas or air changes and the cooling effect may not be the same as it was to start with by time it reaches the end of the target area.
In addition to the handpieces described thus far for ablation of biological matter, other handpieces are known which are outfitted with a spacer serving to adjust a definite distance between the beam outlet opening of the handpiece and the treatment location. The spacer is a roughly rod-shaped object which is fastened to the handpiece by one end portion in the vicinity of the outlet opening for the laser radiation, the opposite end portion being placed lightly on the skin in a location in the immediate vicinity of the treatment location during treatment. This ensures that the laser outlet opening and outlet optics for the laser beam are at an at least roughly constant distance from the treatment location and provides for proper focussing of the laser beam on the treatment location.
It is known to provide spacers of this kind with a suction port on the one hand and to connect the spacers with an exhaust device on the other hand, wherein the suction opening is oriented in such a way that ablation waste products such as particles and fumes are intercepted by the suction port and carried away to the exhaust device through the spacer. However, it is disadvantageous that these arrangements only operate effectively when the suction port in the spacer can be positioned in the immediate vicinity of the laser beam or treatment location and can also remain there. As soon as the distance between the laser beam and suction opening increases, as is the case, e.g., when treating larger skin surfaces by means of laser scanners, the effectiveness of this exhaust device decreases as the distance increases between the laser radiation and the suction port.